The purpose of this project was to catalogue the kinetics of the appearance of cytokines and other mediators of inflammation in an experimental inflammatory response in man. For this study blisters were raised on the forearms of human subjects using a suction blister device. One hour after the blister was raised the blister fluid was evaluated for cells and mediators. The floor of the blister was scrapped for assessment of cell content. A lucite template containing a 1 ml chamber was placed over the blister floor and then filled with 70% autologous serum and the accumulation of cells and mediators into the blister fluid monitored over time. The data indicated that neutrophils increased in the blister fluid throughout 24 hours of study with less than 5% of the cells being mononuclear cells under these conditions. Interestingly, over the first 5 h the floor of the blister contained about 40% mononuclear cells. Neat blister fluid contained small but significantly greater amounts of C5a, LTB4, I1-4, Il-8 and Gamma-interferon compared with simultaneously obtained peripheral blood plasma. These mediators continued to increase with Gamma-interferon peaking at about 6 hours and C5a, LTB4 peaking at 8-12 hours and Il-4 and Il-8 peaking at 24 hours. The following mediators were not observed before 8 hours and then continued to increase through 24 hours: TNF-Alpha, Il-1Beta, and GM-CSF. Il-1Alpha and Il-2 were not detected in the blister fluid. Thus, different cytokines appear in this experimental inflammatory focus with different kinetics and the source and regulation of the appearance of these mediators now needs to be studied.